Conventional lubricants, such as oil or grease, in bearings that are used in extreme or dry environments can deteriorate quickly. In low temperatures, conventional lubricants can cause higher friction torque. In a vacuum, conventional lubricants can out-gas. Others have attempted to provide dry lubricants for bearings.
The Barden Corporation, 200 Park Avenue, Danbury, Conn. discloses a dry-film lubricant. The dry-film lubricant is integrated within the cage. As the bearing rotates, small amounts of the lubricant from the cage are deposited onto the ball bearings and the raceways.
Another lubricant is disclosed by SKF, 890 Forty Foot Road, Lansdale, Pa. The lubricant is based on graphite, molybdenum disulfide (MoS2) and a resin binder. The lubricant is injected into the free space of the bearing and cured until it solidifies. The dry lubricant maintains a very thin film on the raceways and rolling elements to avoid metal-to-metal contact and to protect against damage from solid contaminants.
U.S. Pat. No. 5,356,227 (Sibley et al.) discloses a solid-lubricated bearing assembly including an outer bearing ring, an inner bearing ring, a cage and a plurality of balls arranged within pockets in the cage. The lubricating member is preferably carbon graphite and leaves a thin graphite lubricating film on the assembly. The lubricating member disclosed is an insert arranged within the interior surface of the cage pockets.
International Patent Application No. WO 2011 057654 (SKF A F, et al.) discloses a bearing assembly with active oil lubrication; the bearing assembly includes at least one rolling element bearing and at least one lubrication device. The rolling element bearing includes an inner ring, an outer ring and at least one set of rolling elements disposed within a cavity of the bearing on opposing inner and outer raceways. The lubrication device includes an oil reservoir and a pump drive mechanism. The pump drive mechanism is an electro-osmotic member which pumps a drive fluid, whereby the drive fluid exerts pressure on an oil reservoir in order to effect a supply of oil to the rolling contact zone.
These disclosures do not provide a dry lubricant for a bearing cage where the dry lubricant is embedded within the cage and operatively arranged to actively press against the rolling elements and lubricate them.
Thus, there has been a long-felt need for an improved dry lubrication means for bearings which increases the life of the bearing.